The Big Bang Theory

After their wedding, Amy and Sheldon go on their honeymoon.

Sheldon and Amy are baffled by the gift Penny and Leonard got them for their wedding; and Raj decides he wants his father to find him an arranged marriage.

The Wolowitzes' life gets complicated when Stuart brings his new girlfriend home; meanwhile Penny and Leonard talk about starting a family.

When Sheldon won't tell anyone why he's never mentioned Tam (ROBERT WU), his childhood best friend, Leonard takes matters into his own hands. JERRY O'CONNELL guest stars.

Sheldon sabotages Amy's career and gets a ghostly visit from an old friend; Meanwhile Raj refused Howard's offer to co-host a planetarium show.

When Howard dresses up as Sheldon for Halloween, Sheldon seeks retaliation; meanwhile Penny doesn't remember her first kiss with Leonard.

Leonard regrets his newfound authority at work when he's responsible for distributing grant money; and Bernadette turns the playhouse into her hideaway.

Sheldon tries to bond with Amy's parents. Meanwhile, Raj and Anu attempt to get physical.

Sheldon and Amy are devastated to learn that Super-Asymmetry has already been disproven. Meanwhile, Bernadette has Stuart's girlfriend (LAUREN LAPKUS) teach her Fortnite.

Sheldon seeks advice from the only person who can help him – his younger self (guest star IAIN ARMITAGE). And Bernadette helps Howard with a Magic Castle audition.

Penny & Leonard organize a paintball game that results in mayhem when Sheldon is jealous of Amy, Raj catches Anu with her ex, and Stuart doesn't want to move in with Denise.

Penny's old boyfriend, Zack, and his wife want a baby, but when Zack is infertile, they ask Leonard to help. Meanwhile, Raj attempts to mend things with his ex-fiancée Anu.

When Sheldon and Amy's Super Asymmetry Theory is proven by two physicists from Chicago, they're thrilled – until they try to kick Amy off their Nobel Prize nomination!

Sheldon is thrilled to help Howard & Bernadette navigate bureaucratic paperwork… until he discovers they are breaking the law!

Penny tries to seduce an abstaining Leonard in an attempt to ruin his plan to be a sperm donor for her ex-boyfriend. While Howard, Bernadette, Raj & Anu board the "Vomit Comet."

The guys try to crash Wil Wheaton's celebrity Dungeons & Dragons game involving WILLIAM SHATNER, JOE MANGANIELLO, KAREEM ABDUL-JABBAR and KEVIN SMITH.

While Penny and Bernadette are away at a pharmaceutical sales convention in San Diego, Sheldon, Leonard, Howard, Raj and Amy experiment on the Wolowitz kids.

When competitors Pemberton and Campbell (SEAN ASTIN and KAL PENN) charm America on a publicity tour, Sheldon and Amy try to win over Nobel laureates.

When Howard buys a scooter like the one he had years ago, he and Raj relive their glory days; meanwhile, Amy has a meltdown over possibly winning a Nobel.

While Penny encourages Leonard to stand up for himself in a physics study, Raj is worried after publishing a paper suggesting he may have discovered alien life.

When Barry Kripke finds proof that Dr. Pemberton plagiarized his thesis in college, Sheldon and Amy try to take the high road in their quest for the Nobel Prize.

Leonard is pleasantly surprised when his mother (CHRISTINE BARANSKI) visits and is genuinely kind toward him – until he finds out the real reason she's there.

Everything changes as Sheldon and Amy await big news.

Bernadette and Wolowitz leave their kids for the first time; Penny and Leonard try to keep a secret; Sheldon and Amy stick together; and Koothrappali makes a new friend, as the gang travels together into an uncharted future.